Sen. Jim DeMint is set to become the top Republican on the Commerce Committee — a promotion that could cause heartburn among GOP leaders but one they appear unlikely to block.

The conservative South Carolina Republican maintains a sometimes antagonistic relationship with Conference leadership and some of his rank-and-file colleagues. Republican leaders thwarted DeMint’s bid to join the Finance Committee when a seat opened in 2009, and there is speculation among some Capitol Hill observers that he could be passed over for the top GOP spot on Commerce despite the usually sacred treatment of Senate seniority — particularly if Republicans win the majority and the slot becomes a chairmanship.

But Republican operatives who follow the Senate predicted that GOP leaders would not stand in the way of DeMint becoming the ranking member or chairman of the committee. One GOP insider said it wouldn’t be worth antagonizing conservative grass-roots activists and interest groups that would take offense. And Senate Minority Leader Mitch McConnell (R-Ky.) would no doubt be pilloried by tea party activists for the move — a scenario the would-be Majority Leader can’t afford if he wants to avoid a primary in 2014 as well as repair relations with conservatives who are angry with his backing of now-Sen. Rand Paul’s (R-Ky.) primary challenger in 2010.

DeMint, who has been less combative with his fellow Republicans this Congress, said he looks forward to leading his party on Commerce next year and to hopefully becoming chairman. DeMint noted that current Chairman Jay Rockefeller (W.Va.) was his assigned Democratic mentor when he first arrived in the Senate, and he expressed confidence the two could work together to advance legislation. DeMint also remains interested in joining Finance, an endeavor in which GOP sources suggested that he could continue to face internal Conference resistance.

“I’d very much like to run the Commerce Committee, much rather it be a chairman than a ranking position,” DeMint said Wednesday in an interview. “I’d also like to be on the Finance Committee, which I was in line for last time.”

DeMint’s seniority on Commerce can be traced to the coming retirements of ranking member Kay Bailey Hutchison (R-Texas) and Sen. Olympia Snowe (Maine), currently the second-ranking Republican on the panel. If DeMint does not end up as the next Republican leader on Commerce for whatever reason, the top spot could fall to Republican Conference Chairman John Thune (S.D.), who is just behind his South Carolina colleague in seniority.

Rockefeller, who has a good relationship with Hutchison and often praises her, appears less confident than DeMint that the two would be able to run the panel smoothly. The West Virginian speculated that DeMint could be “very difficult” to work with but said he would do his “very best.” Rockefeller went so far as to say he does not expect DeMint to succeed Hutchison, but he declined to elaborate on why he believes this.

“I don’t think it’s going to end up being him; I’ll just say that,” Rockefeller said. “He’s a nice person individually. ... He’s been OK on the Commerce Committee.”

Although Senate seniority generally governs ascension in committee, Republicans vote on their ranking members or chairmen and could choose a more junior Member to lead them on a particular panel. In 2004, then-Sen. Arlen Specter (R-Pa.) faced resistance to his rise to the Judiciary chairmanship, but he was eventually installed in that powerful post despite concerns about his centrist record.

A GOP Senate aide said that Commerce Republicans, who generally share DeMint’s conservatism, were unlikely to pass him over for ranking member or chairman — even if they disapproved of his treatment of fellow Republicans.

One former Senate GOP leadership aide who monitors the chamber was less convinced but said that DeMint has been much less antagonistic this Congress than he was during the 111th, reducing the likelihood that the Republicans on Commerce would move to demote him.

“If Sen. DeMint began criticizing his fellow colleagues and trashing the leadership like he did in the last Congress, there would be an effort to replace him as the top Member,” the former leadership aide said. “However, he has been much more focused this year on other issues, which could be to his benefit.”

DeMint said his agenda for the Commerce Committee, should he take the helm next year, would be to focus on updating and modernizing television broadcasting and telecommunications regulations, which he referred to as “antiquated,” as well as rules governing the Internet. The Senator said additional policy areas under Commerce’s jurisdiction, including aviation and transportation, interest him and would receive his attention.

A Republican lobbyist said DeMint and his anti-tax philosophy would be welcomed by industries with business before the panel.

The Senator is a staunch opponent of earmarks, a hallmark of how K Street has long used the legislative process to deliver results for clients. But earmarks are currently banned in both the House and Senate, and DeMint is unlikely to face opposition from lobbyists for supporting a policy that has been widely embraced as a political reality by Democrats and Republicans.

“The earmark fight is over until we get the deficit picture fixed,” the Republican lobbyist said.